Revert "Fixed corrupted disk due to nbd"

This reverts commit c08e79a489db5d5e79bdf3aa93d5118dd44e3548.
Merge branch 'kameleon2-dev' of git+ssh://scm.gforge.inria.fr//gitroot/kameleon/kameleon into kameleon2-dev
Update and iprove contrib setup steps
Merge branch 'kameleon2-dev' of git+ssh://scm.gforge.inria.fr//gitroot/kameleon/kameleon into kameleon2-dev
clean templates steps and upgrade network_config
debug network_config
ensure to always run bash commands in an environment compatible with most linux distributions
Do not use the option 'no-cache' with qemu-nbd
Merge branch 'kameleon2-dev' of github.com:oar-team/kameleon into kameleon2-dev

Conflicts:
	templates/steps/setup/debian/network_config.yaml